Transcription And Translation. Flashcards
What happens in Transcription?
• DNA is in the nucleus of the cell and can’t get out because it’s too big.
• The sequence of bases in DNA is used as a code to make a similar molecule called mRNA, which is single stranded and contains all the same bases, except that thymine is replaced by uracil.
• RNA polymerase is an enzyme that makes the mRNA.
• It binds to a region of non-coding DNA in front of a gene.
• The two DNA strands are unzipped/separated and the RNA polymerase moves along one of the strands of the DNA to use the DNA as a template to make mRNA.
• Free bases found in the nucleus are used to make the mRNA.
• Base pairing between the DNA and RNA ensures that the mRNA is complementary to the gene.
Once the mRNA is made, and after processing, the mRNA moves out of the nucleus and goes to a ribosome in the cytoplasm.
What happens in Translation?
• The mRNA reaches the ribosome.
• In translation, tRNA also have an anticodon; a set of three nucleotides that will then bind to a matching mRNA codon through base pairing.
• RRNA reads the bases of the nucleotides in codons that code for amino acids.
• As tRNAs enter slots in the ribosome and bind to codons, the amino acids that they also carry on their opposite end will be linked to the growing polypeptide chain in a chemical reaction.
• After a stop codon is read, the growth stops and the amino acids fold to form a protein.
• Even though some regions of DNA are non-coding, they are still involved in protein synthesis.
Define Transcription:
The process in which a cell makes an RNA copy of a piece of DNA.
Define Translation.
The process in living cells in which proteins are synthesised due to mRNA and DNA.
What is a Codon?
A sequence of three bases in the DNA that codes for one amino acid in the protein.
The order of the bases in a gene determines what?
The order of the amino acids in the protein.
Each gene contains what?
A different sequence of bases.
